Background: We investigated whether consumers’ perception of a café latte beverage would be influenced by the colour (transparent, white or blue) of the mug from which it was drunk.
Results: In experiment 1, the white mug enhanced the rated “intensity” of the coffee flavour relative to the transparent mug. However, given slight physical differences in the mugs used, a second experiment was conducted using identical glass mugs with coloured sleeves. Once again, the colour of the mug was shown to influence participants’ rating of the coffee. In particular, the coffee was rated as less sweet in the white mug as compared to the transparent and blue mugs.
Conclusions: Both experiments demonstrate that the colour of the mug affects people’s ratings of a hot beverage. Given that ratings associated with the transparent glass mug were not significantly different from those associated with the blue mug in either experiment, an explanation in terms of simultaneous contrast can be ruled out. However, it is possible that colour contrast between the mug and the coffee may have affected the perceived intensity/sweetness of the coffee. That is, the white mug may have influenced the perceived brownness of the coffee and this, in turn, may have influenced the perceived intensity (and sweetness) of the coffee. These results support the view that the colour of the mug should be considered by those serving coffee as it can influence the consumer’s multisensory coffee drinking experience. These results add to a large and growing body of research highlighting the influence of product-extrinsic colour on the multisensory perception of food and drink.
Alex’s Notes: The title is an excellent question that was brought about “serendipitously” when the author was conversing with a barista. To find an answer, the researchers recruited 18 men and women between the ages of 18 and 62 years (average 31.5 years) to drink 200mL of café latté. Six were given the drink in a white porcelain mug, six in a transparent glass mug, and six in a blue porcelain mug.
The mug textures were identical and as close to identical in shape, size, and weight as possible. Even the same metal spoon was used in preparation of each drink (rinsed with water between drinks), and the temperature and lighting kept constant in an attempt to reduce as many confounding variables as feasible. It was a single blinded study whereby the participants were told that the purpose of the study was to assess certain characteristics of coffee. Once the participants consumed their drink, they rated its perceived bitterness, sweetness, aroma, flavor intensity, quality, and acceptability using a visual analog scale.
The café latté was rated significantly more intense when served from the white ceramic mug than when served from the clear glass mug; over twice as intense to be more specific. The blue mug was not significantly different from the others, although it was in between the white and clear mugs for intensity rating, and none of the other ratings were significantly difference between any of the mugs. Still, it is interesting to see trends in the data. For instance, the most “intense” drink (white mug) was also rated as the bitterest, aromatic, and of highest quality, while the acceptability was the lowest. The glass mug with the lowest intensity followed the exact opposite trend, with the blue mug falling the middle of all these.
Those mugs were not similar!
Yes, you’re right. There were indeed slight differences in shape and texture of the mugs. Also, the sample size was pretty small. Thus, a second experiment was done with 36 volunteers (only six were men) aged between 17 and 66 years (average 40 years). It was the exact same experiment except that instead of mugs, three groups of 12 persons were given their café latté in identical glass mugs that only differed in the color of rubber grip around them (white, blue, or no grip).
This time, the drink was rated as significantly less sweet when served from the white mug relative to the see-through, glass mug or the blue mug, with none of the other comparisons reaching statistical significance. Again though, trends are interesting. Mr. not sweet white mug was also the bitterest, aromatic, and intense café latté.
How do you like your coffee?
The authors argue that implicit judgments regarding the intensity of the white mug may be transferred to the coffee causing it to be perceived as more intense than the coffee served in the other mugs. Similar to previous research, the white background of the mug may have influenced the perceived “brownness” of the coffee that implies a stronger brew.
So there you have it. Yet more evidence of the ever subtle ways our eating environments influence our eating experience. And now you have a trick up your sleeve. If you have guests over and they like their coffee strong, give it to them in a white mug.